Re: [ogpx] URI schema for virtual world locations?

[Meadhbh Hamrick <[e-mail]>]

it's important because one of the functions of the protocol will be
for clients to inform servers where they wish their avatars to appear
in the virtual world. virtual objects will be moving as well, and
simulators will need to communicate with user agents the moral
equivalent of "box number 5 just moved to location <x,y,z>."

VWRAP is a protocol for interaction between systems that have
characteristics similar to OpenSimulator and Second Life. Both systems
use meters in a rectangular coordinate system to describe position.

There has been discussion in the past about supporting multiple
coordinate systems, but the implementers believed it would introduce
unneeded complexity. Requiring that ALL compliant systems support ALL
possible representational systems seemed like an invitation to
incompatibility.

VWRAP does not mandate what coordinate system your implementation uses
internally, it only mandates what coordinate system you use to
communicate with other systems. If you wish to use polar coordinates
measured in femtoparsecs in your implementation, that is your
business. but when it's time to communicate with the outside world
(using VWRAP), you'll have translate into/out of meters in a
rectangular coordinate system.

this is not because we're rectangular bigots, it's because many of us
believe that picking a single representational system will reduce
complexity of the protocol.

-cheers
-meadhbh

On Fri, Jan 22, 2010 at 7:22 AM, Richard L. Barnes <[e-mail]> wrote:
> It's not clear to me why the protocol needs to define coordinates,
> especially given that different servers might have different notions of
> place.  One server might think of space in terms of coordinates in meters,
> another in polar coordinates, another in terms of polygons that represent
> some construct known only to the server.
> So when we're talking about referring to points in space, it seems like it
> would make sense to have two parts: One piece of information that gets you
> to the right server, and one that tells the server what location is being
> referenced (in whatever frame it thinks in).
> To make an analogy, in the HTTP URI <http://example.com/this/is/a/path>, the
> authority part "example.com" gets you to the right server, and the meaning
> of the path component "this/is/a/path" is completely up to the server (it
> can be opaque to the user).
>
> --Richard
>
>
> On Jan 22, 2010, at 9:25 AM, Frans wrote:
>
> I like this idea too, makes a lot of sens. +1
>
> On Thu, Jan 21, 2010 at 10:10 PM, Meadhbh Hamrick
> <[e-mail]> wrote:
>>
>> hmm. i kinda like this idea.
>>
>> we may want to choose a rectangular coordinate system as the default.
>>
>> so yeah, maybe the mapping service is "the thing" that defines what
>> we're now alternately calling a virtual world, grid or instance. so we
>> could have a simple service like this that describes the grid:
>>
>> %% grid/info
>> << {
>>  grid_name : string,
>>  coordinates : string,
>>  map_service : uri
>> }
>>
>> and you could plug in values of "spherical" or "cylindrical" in the
>> coordinates entry, but have "rectangular" be the default. the
>> "map_service" URI could be the URI used to convert a region name +
>> point in space into a URI for requesting services like teleport, map
>> tiles, spatial chat, etc.
>>
>> so... for example... i could have a grid/info entry for SL's vaak test
>> grid at http://util.vaak.lindenlab.com/. when you did a HTTP GET on
>> it, you would get the blob:
>>
>> <?xml version="1.0"?>
>> <llsd>
>>  <map>
>>    <key>grid_name</key>
>>    <string>vaak</string>
>>    <key>map_service</key>
>>    <uri>http//util.vaak.lindenlab.com/services/map</uri>
>>  </map>
>> </llsd>
>>
>> the map service at http//util.vaak.lindenlab.com/services/map could be
>> queried to get information and/or caps to access locations. so you
>> could construct a service like:
>>
>> %% location/info
>> << {
>>  teleport_cap : uri,
>>  map_tile : uri,
>>  spatial_chat_cap : uri
>> }
>>
>> so when you did a get on
>>
>> http//util.vaak.lindenlab.com/services/map?location_x=128&location_y=128&location_z=32&region_name=Ahern
>> you might get a response like:
>>
>> <?xml version="1.0"?>
>> <llsd>
>>  <map>
>>    <key>teleport_cap</key>
>>
>>  <uri>http://sim1.vaak.lindenlab.com/c/0953E063-5B31-4B62-B218-A7C0CE1FC391</uri>
>>    <key>map_tile</key>
>>    <uri>http://s3.amazonaws.com/foo/bar/ahern.jpg</uri>
>>    <key>spatial_chat_cap</key>
>>
>>  <uri>http://sim1.vaak.lindenlab.com/c/4AFA1BAF-4FAD-45A5-A683-6244BC81A660</uri>
>>  </map>
>> </llsd>
>>
>> and the teleport_cap would be the one that gets used if someone wanted
>> to teleport to the location.
>>
>> hope this makes sense.
>>
>> -cheers
>> -meadhbh
>>
>
> --
> Jeroen Frans
> Virtual World Technology Specialist.
> TheVesuviusGroup.com
> SL: Frans Charming
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